Multi-temperature atomic ensemble: nonequilibrium evolution after ultrafast electronic excitation

Abstract

Ultrafast laser radiation or beams of fast charged particles primarily excite the electronic system of a solid driving the target transiently out of thermal equilibrium. Apart from the nonequilibrium between the electrons and atoms, each subsystem may be far from equilibrium. From the first principles, we derive the definition of various atomic temperatures applicable to electronically excited ensembles. It is shown that the definition of the kinetic temperature of atoms in the momentum subspace is unaffected by the excitation of the electronic system. When the electronic temperature differs from the atomic one, an expression for the configurational atomic temperature is proposed, applicable to the electronic-temperature-dependent interatomic potentials (such as ab-initio molecular dynamics simulations). We study how the configurational temperature behaves during nonthermal phase transition, triggered by the evolution of the interatomic potential due to the electronic excitation. It is revealed that upon the ultrafast irradiation, the atomic system of a solid exists temporarily in a multi-temperature state: separate equilibria in the momentum and configurational subspaces. Complete equilibration between the various atomic temperatures takes place at longer timescales, forming the energy equipartition. Based on these results, we propose a formulation of multi-temperature heat transport equations.

References in corpus (23)

• Density-functional tight-binding for beginners
• A Dynamical Approach to Temperature
• Microscopic expressions for the thermodynamic temperature
• Entropy based fingerprint for local crystalline order
• Electron-phonon coupling and energy flow in a simple metal beyond the two-temperature approximation
• Inconsistent thermostatistics and negative absolute temperatures
• Electron-phonon coupling in metals at high electronic temperatures
• Thermal and nonthermal melting of silicon under femtosecond x-ray irradiation
• Various damage mechanisms in carbon and silicon materials under femtosecond x-ray irradiation
• Ionization and expansion dynamics of atomic clusters irradiated with short intense VUV pulses
• Frontiers, challenges, and solutions in modeling of swift heavy ion effects in materials
• Consistent description of fluctuations requires negative temperatures
• Negative temperatures and the definition of entropy
• Soft x-rays induce femtosecond solid-to-solid phase transition
• Classical dynamical coarse-grained entropy and comparison with the quantum version
• Configurational temperature of charge-stabilized colloidal monolayers
• Modeling time-resolved kinetics in solids induced by extreme electronic excitation
• Self-learning analytical interatomic potential describing laser-excited silicon
• Temperature dependence in interatomic potentials and an improved potential for Ti
• Electronic nonequilibrium effect in ultrafast-laser-irradiated solids
• Metallic water: transient state under ultrafast electronic excitation
• Damage threshold in pre-heated materials exposed to intense X-rays
• Nonthermal effects in solids after swift heavy ion impact

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